赣南葛藤嘴稀土矿风化壳剖面元素迁移特征研究

近年来在赣南葛藤嘴地区首次报道了以浅变质岩为母岩的风化壳离子吸附型稀土矿床,这一发现极大地拓宽了离子吸附型稀土矿床的找矿空间。对赣南葛藤嘴浅变质岩离子吸附型稀土矿床的原岩与风化壳进行研究,共采集了3个变质沉凝灰岩原岩样品和12个风化壳剖面全风化层样品,开展元素地球化学特征分析,以探讨风化壳剖面中元素迁移与稀土元素富集特征。研究结果表明,风化壳风化程度已进入到风化中晚期,质量平衡计算显示其主量元素Ca、Na、P等元素基本淋滤殆尽,Si、Al、Mg、K迁出程度依次增强,Fe、Ti等元素保持相对稳定;稀土元素除Ce外,其他稀土元素均表现出明显的迁入特点;风化壳剖面全风化层样品的总稀土元素含量约为其原岩的3.4倍,稀土元素的富集主要由于原岩中富含稀土元素的矿物发生分解,释放的稀土阳离子在随地下水迁移过程中,被黏土矿物吸附导致。     

试论我国区域经济发展的三种战略

区域经济的协调发展是构建和谐社会的基础.研究党的三代中央领导集体的区域经济发展战略,对我国过去的区域经济建设实践进行历史性客观总结,得出规律性的启示,对今天新一轮的区域经济发展有着十分重要的理论借鉴意义.     

岩浆岩与变质岩野外识别方法探讨

岩石根据成因可分为岩浆岩、沉积岩和变质岩三大类,其中,地壳中沉积岩含量最少。对岩浆岩和变质岩的野外识别与描述的方法进行了探讨,分别给出了其识别标志、步骤、方法和描述内容。     

二摄象机式立体电视系统几个参数的分析

本文讨论了二摄象机式立体电视摄象系统的参数:深度分辨力,立体区域,显示畸变量;以及这些参数之间的相互关系。     

辽西太古代“建平变质杂岩”的变质作用演化

“建平变质杂岩”是辽宁省西部太古代的最下部的地体,它由连续性很差的表壳岩、TTG岩石及其它深成侵入岩构成。基本岩石类型有镁铁质岩石(包括角闪岩、辉石岩、斜长角闪岩等)、麻粒岩、紫苏花岗岩、片麻岩及少量的超镁铁质岩和磁铁石英岩。常见且主要的矿物相是斜方辉石、单斜辉石、石榴石、角闪石、斜长石和石英。岩相学研究确定了指示变质作用不同阶段的三个变质反应的存在,并且它们与推测的矿物相的转化关系吻合,结合地质温压的限定,本文得出了本区太古代末期的强烈的变质热事件的反时针的P-T-t演化轨迹,并推测出此变质热事件与大量的岩浆增聚密切相关。     

Preliminary study of microscale zircon oxygen isotopes for Dabie-Sulu metamorphic rocks： Ion probe in situ analyses

151 in situ analyses of oxygen isotopes were carried out by ion micro-probe for zircons from 8 localities of HP-UHP metamorphic rocks including eclogites in the Dabie-Sulu terrane. The results show significant heterogeneity in δ^18O values, with variation in different rocks from -8.5‰ to 9.7‰ and within one sample from 2‰ to 12‰. No measurable difference in δ^18O was observed between protolith magmatic (detrital) zircons and metamorphic recrystallized zircons within analytical uncertainties from the ion micro-probe measurements. This indicates that the metamorphic zircons have inherited the oxygen isotopic compositions of protolith zircons despite the HP to UHP metamorphism. According to their protolith ages from zircon U-Pb in situ dating by the same ion micro-probe, two groups of oxygen isotope composition are recognized, with one having δ^18O values of 6‰-7‰ for old protolith of 1.9-2.5 Ga ages and the other 0‰-2‰ for young protolith of 0.7-0.8 Ga ages. The latter anomalously low δ^18O values of zircons indicate that the magma has had the obvious involvement of meteoric water when forming the young protolith of high-grade metamorphic rocks. This may be correlated with the snowball Earth event occurring in South China and the world elsewhere during the Neoproterozoic.     

陨石冲击变质作用的一般特征

来自地球之外的陨石对地球的冲击作用，必对地球产生一系列重要的影响，陨击变质作用即是其中之一。陨击变质作用形成特征的陨击角砾岩及陨击熔岩，常见造岩矿物在陨击变质作用下的变形、变质、转化是陨击变质作用最重要的特征。根据陨击变质岩及其中主要造岩矿物的变形、转化特征可划分出四个陨击变质带：（１）陨击角砾岩化带；（２）石英玻璃（均质）化带；（３）柯石英带和（４）假玄武玻璃带。     

U-Pb zircon dating constraints on formation time of Qilian high-grade metamorphic rock and its tectonic implications

In order to constrain the formation time of high-grade metamorphic rocks in the Qilian Mountains, U-Pb zircon dating was carried out by using LA-ICPMS technique for a paragneiss of the Hualong Group in the Qilian Mountains basement series and a weakly foliated granite that intruds into the Hualong Group. Zircons from the paragneiss consist dominantly of detrital magma zircons with round or sub-round shape. They have 207Pb/206Pb ages mostly ranging from 880 to 900 Ma, with a weighted mean age of 891 ±9 Ma, which is interpreted as the magma crystallization age of its igneous provenance and can be taken as a lower age limit for the Hualong Group. Magma crystallization age for the weak-foliated granite is 875±8 Ma, which can be taken as an upper age limit for the Hualong Group. Accordingly, the formation time of the Hualong Group is constrained at sometime between 875 and 891 Ma. A few zir- cons from both paragneiss and weak-foliated granite display old inherited ages of 1000 to 1700 Ma and young metamorphic ages of Early Paleozoic. The zircon age distribution pattern confirms that the Qilian Mountains and the northern margin of Qaidam Basin had a united basement, with geotectonic affinity to the Yangtze Block. The results also reveal that sediments of the Hualong Group formed by rapid accumulation due to rapid crustal uplift-erosion. This process may result from intensive Neoproterozoic orogenesis due to assembly of the suppercontinent Rodinia.     

大别山超高压变质带的确定及存在的问题

着重报道了大别山超高压变质带的确定依据,其中包括一些特征性超高压变质矿物和超高压变质岩的发展过程。在此基础上,评述了目前国内外地质学家对大别山造山带的研究现状及存在的急需解决的主要问题。